Remove text nodes from the head element when loading the document
Remove text nodes from the head element when loading the document

The head element should only contain metadata content. Also, Dompdf may have difficulties when text content is contained inside the head element (e.g. no block-level parent found errors). As such we'll add the head element to the list of elements where text node children are removed.

BrunoDeBarros/dompdf,dompdf/dompdf,BrunoDeBarros/dompdf,dompdf/dompdf